When incandescent lamp is dc-illuminated to obtain a flickerless illumination with a high brightness, the filament snapping instantly arises an arc to effect a relatively high discharge current through the filled gas.
The arc occurs almostly under a short-circuited condition because the circuit resistance during the discharge is extremely low. Actual measurement showed that the discharge current was up to 200 amperes when the filament of 60-watt incandescent lamp was snapped during illumination with dc 130 volts. The arc discharge current instantly damages the circuit parts.